The present invention relates to ball bearings, and more particularly to ball bearings suitable for high-speed fabrication and assembly and particularly advantageous for use in drawer slides.
Manufacture and assembly of ball bearings typically involves several components and several machining operations. Manufacture of ball bearings for use in inexpensive drawer slides normally necessitates a design decision of whether to sacrifice quality to hold cost down, or alternatively achieve quality at a relatively high price.
One ball bearing structure for use in drawer slides optimizing the balance between cost and quality is illustrated in U.S. Pat. No. 4,243,277, issued Jan. 6, 1981, to Fortuna, and entitled BALL BEARING. This bearing includes a hollow stem having a body defining an inner race, a retention washer mounted on the stem and held in position by swaging the stem, a plurality of balls axially retained between the washer and stem body, and a polymeric outer race member defining an outer race. The outer race member includes three axial diametrical portions with the middle portion being the largest in diameter defining the ball race. Although this structure constituted a noteworthy advance over the prior art, it has subsequently been noted that the bearing suffers two minor drawbacks. First, the ball race is open at both of its opposite sides between the inner race and outer race, permitting dirt and other debris to enter the raceway and foul the bearing. This detracts from the smooth operation of the bearing and also reduces the bearing life. Second, the outer race which is snap-fitted over the balls is capable of bearing only relatively small lateral thrust forces.